Gloeomyces Sheng H. Wu, Mycotaxon, 1996

Gloeomyces Sheng H. Wu, Mycotaxon View in CoL View at ENA 58: 47. 1996. emend.

Basidiomes annual, resupinate, effused, adnate, membranaceous, coriaceous or subcrustose. Hymenophore smooth or slightly tuberculate, greyish white, cream to yellowish-brown, not cracked or densely cracked with age; margin thinning out or abrupt, determinate, indistinct, adnate, paler than or concolourous with hymenophore. Hyphal system monomitic. Generative hyphae simple-septate or nodose-septate, colourless, thin- to slightly thick-walled. Subiculum usually indistinct or absent. Subhymenium thickening, composed of hyphae, gloeocystidia and acanthohyphidia. Gloeocystidia abundant, variable in shape, usually submoniliform with one to several contractions in the upper part, colourless, slight thick-walled. Acanthohyphidia numerous, variable in shape, usually hyphoid or vase shaped with a wide base, sometimes branched, typically colourless, thin-walled, with many small spines in upper part, in some species yellow to brown, thick-walled, with long spines or branches (resemble binding-hyphae), inamyloid, indextrinoid or dextrinoid in some species. Basidia clavate to subcylindrical, colourless, thin-walled, smooth, with two or four sterigmata, bearing a basal septum with or without a clamp connection. Basidiospores ellipsoid, colourless, thin-walled, smooth, amyloid, acyanophilous.

Type species: Gloeomyces graminicola Sheng H. Wu

Notes: In the phylogenetic tree, Gloeomyces formed a well-supported clade. Previously, several species in the clade were placed in Acanthophysellum , viz. Ap. cerussatum , Ap. dextrinoideocerussatum and Ap. lapponicum , but the type of the genus, Ap. lividocoeruleum , was nested within Xylolobus clade ( Wu et al. 2001, Larsson & Larsson 2003). Acanthophysium , typified by Am. apricans and used for species with abundant acanthohyphidia and smooth basidiospores, is a possible name for this clade. Wu et al. (2000) treated Acanthophysium as a synonym of Xylobolus based on the simple-septate hyphae, smooth basidiospores, holocoenocytic nuclear behaviour and phenoloxidase negative reaction of Am. apricans . DNA sequences of Am. apricans are expected to clarify the phylogenetic relationship. Before this, we prefer to use Gloeomyces for the name of the clade, since its type species, G. graminicola was included ( Fig. 1 View Fig ).

Morphologically, species of Gloeomyces are characterized by having resupinate basidiomes, well-developed acanthohyphidia and smooth basidiospores ( Wu 1996, Núñez & Ryvarden 1997). The coloured thick-walled binding hyphae in some species of the genus might be a special form of the acanthophyses. Aleurodiscus s. str. can be easily separated from Gloeomyces by possessing ornamented basidiospores or thick-walled smooth basidiospores in A. fujii .

Based on morphological and molecular evidence, a new species is described and illustrated, and 11 new combinations are proposed in Gloeomyces . We believe that more species of Aleurodiscus s. lat. will be moved to Gloeomyces after sequencing of authentic specimens.

The ITS similarity between MH109052 View Materials (from He 5283, paratype of A. isabellinus ) and AF506448 View Materials (from Wu 9210-12, holotype of G. graminicola ) is 99.2 % with three differences of total 357 base pairs. Gloeomyces graminicola originally described from Taiwan was also found in Yunnan Province, southwestern China (Liu 2019), whereas A. isabellinus was reported only from Yunnan Province. Morphologically, the two species are similar to each other except that A. isabellinus has abundant colourless acanthohyphidia. However, this might be because that the specimens were at different stages, since the specimens without basidia usually have well-developed sterile organs. Thus, considering both molecular and morphological evidence, we treat A. isabellinus as a synonym of G. graminicola .